> 2003 was the first device that resembled a smartphone.

I had a Handspring Visor when they were first released (around 2000), and while it was just a PDA on its own, there was a phone module that slid into the back, making it a smartphone. After that, I had almost all of the Treo's starting around 2002, which (what I think) were the first all-in-one smartphones.